Recently, developments have been made for fuel cell systems using, as energy sources, fuel cells that generate electrical power through a chemical reaction between a fuel gas and an oxidant gas serving as reactant gasses. In order to generate electrical power efficiently in a fuel cell system, the amounts of supply of the fuel gas and the oxidant gas need to be optimally adjusted. However, since the amounts of supply of the reactant gasses vary in accordance with usage environments, such optimal adjustment is not easy. For example, when the fuel cell system is used in a highland, the density of the air is lowered and the amount of the oxidant gas supplied to a fuel cell becomes insufficient, thereby resulting in the efficiency of power generation being lowered. In order to solve such a problem, in the fuel cell system disclosed in patent document 1, when the atmospheric pressure is lowered, the amount of oxidant gas supplied to the fuel cell is maintained by increasing the rotation speed of the compressor.
Patent document 1: JP2000-48838 A